<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <script src="js/jquery-3.4.1.min.js"></script>
    <script src="js/bootstrap.bundle.min.js"></script>
    <script src="js/bootstrap.min.js"></script>
    <style>
        div {
            border: solid 1px red;
        }
    </style>
</head>

<body>
    <!-- 
        class="container"：可以根据浏览器的窗口大小进行自适应和居中
        ps：会设置padding属性为15
     -->
    <div class="container">
        <h2>hello bootstrap</h2>
    </div>

    <div class="container-fluid">
        <h2>hello bootstrap</h2>
    </div>
</body>

</html>